Relationship between parents' report rate of twin language and factors related to linguistic development: older sibling, nonverbal play and preschool attendance.

The definition and nature of twin language has been a focus of recent studies concerned with the phenomenon. There has been a call for a tighter definition and understanding of the meaning of twin language (Thorpe et al., 2001). This article sought to identify social factors associated with the parent report of twin language and thus provide further understanding of the phenomenon. Data from 583 mothers of twins aged 25 to 59 months were analysed using multiple logistic regression. Factors included in the modelling of parent report twin language included social experience factors such as presence of siblings, attendance at preschool education and reports of non-verbal play. It was found that twin pairs who didn't have an older sibling, who showed frequent non-verbal play and who didn't attend preschool were more likely to have a twin language. Moreover, in the group not having an older sibling, the influence of whether twins attended preschool or not was strong and the odds ratio was 0.589 (95% confidence intervals 0.360-0.963). The findings suggest that social experience factors are important predictors of the parent reporting of twin language.